The present invention is directed to the delay of real-time information signals, such as audio or video signals, and is particularly concerned with the selective, human responsive recording of such information signals.
There are many situations in which it is desirable to be able to selectively record information that is presented in real time. For example, in the classroom environment, a student may want to record the more significant portions of a lecture being given by an instructor. Typically, those portions of the lecture which the student deems worthy of recording might comprise only 20-30% of the total lecture. If the student uses a conventional magnetic tape recorder to record the lecture in real time by selectively turning the recorder on and off, it is likely that the first few words of each new significant portion of the lecture will be lost. This loss is due to the delay occasioned by the time it takes the student to realize that a significant topic is being discussed and to actuate the recorder. Even for students who are alertly following the lecture, this delay might be in the neighborhood of 8 seconds.
Accordingly, for fear of losing the information that is spoken during this delay period each time before the recorder is turned on, the student might leave the recorder on during the entire lecture. However, the recording of the entire lecture is undesirable since it could later require a significant amount of time to review and edit the less important segments of the recorded information from that which is desired to be retained.
Other situations which impose similar considerations include intelligence gathering operations, interviews, the video recording of newsworthy items, and the monitoring of secure areas, to name a few.
To overcome the limitations associated with selective actuation of conventional real-time recorders, various systems have been devised which provide a time-delayed recording capability. In the past, these systems have been primarily mechanical in nature, and hence subject to wear and tear and possibly eventual failure. Typically, one of these systems might consist of two magnetic tapes. One of these tapes can be in a continuous loop wherein the real-time audio information is recorded on the tape at one point in its path of travel and subsequently reproduced from the tape at a second point downstream of the recording point, so as to provide a delayed audio signal. This delayed signal can then be selectively applied to a second tape under the control of the person who desires the information so as to record an edited version of the lecture. Representative patents disclosing this general type of a time delayed recording system include U.S. Pat. Nos. 3,028,454, 3,812,530 and 4,408,309.
While the basic approach to the time delayed information recording that is employed in these types of systems is sound, it is desirable to implement this approach without the need for a mechanically based system. More particularly, it is an object of the present invention to provide a system for delaying an audio or other real-time information signal using state-of-the-art information storage technology, particularly semiconductor storage, to thereby provide a totally electronic and portable system that enables an observer to determine whether information is important before it is recorded.